1.2.1 Operating systems Flashcards
Operating systems
Define ‘kernel’
The kernel loads and unloads software into main memory
Operating systems
Define ‘driver’
Controls and communicates with hardwaere
Operating systems
Define ‘utilities’
Programs that perform background tasks
Operating systems
Define ‘user interface’
A way to allow users to interact with the computer system
Operating systems
Define ‘operating system’
Software which controls how a computer operates
Operating systems
Define ‘scheduling’
The process of assigning resources to tasks
Memory management
Describe the process of memory management
Ensuring programs cannot access each other’s data
Ensuring the RAM’s free space is being used efficiently
Memory management
What are the two methods of managing the space used in main memory?
Paging
Segmentation
Memory management
What is memory segmentation?
The allocation of segments of memory to a process, to allow it to run
Memory management
What sections are found within each segment during memory segmentation?
Stack segment
Free memory
Data segment
Code segment
Memory management
What is the role of the code segment?
Where the program instructions for the process reside
Memory management
What is the role of the data segment?
Memory space for the variables the program will use
Memory management
What is the role of the stack segment?
Stores the address of the line in the program the processor was on when it got interrupted by a subroutine
Memory management
What is the role of the free memory?
Available memory space put aside for the stack overflow
Memory management
What is virtual memory?
An area on the hard disk that has been marked as additional main memory, to increase the size of RAM temporarily
Memory management
How does the CPU access data held in virtual memory?
The memory manager swaps data between RAM and virtual memory for the CPU to access, as it can only reach data stored in RAM
Memory management
What is meant by ‘disk thrashing’?
When the hard disk is excessively used for virtual memory storage, and data is being transferred repeatedly between RAM and virtual memory
Memory management
What is a ‘page’?
A fixed sized area of memory
Memory management
How does the memory manager keep track of pages?
Each page has an associated number, kept track of in a page table
Memory management
What happens when RAM is getting full, in regards to memory being stored as pages?
The memory manager identifies less used pages and cuts them to virtual memory
Memory management
Describe what pagination is and when it is used
Pagination is the process of separating memory into pages
It is used when managing and using virtual memory
Memory management
What are the similarities between segmentation and pagination?
Both are a way of dividing up memory
Both are assigned and managed by the memory manager
Memory management
What are the differences between segmentation and pagination?
Segmentation is used to load and unload processes, whereas paging is used when swapping data to virtual memory
The size of a segment always varies, whereas a page is a fixed size
Memory management
What is a ‘memory leak’, and what can happen because of one?
A memory leak is when segments contained finished with processes aren’t remarked as free, and therefore prevent more data from being stored in memory
Due to a memory lea, the system can eventually run out of memory